Effects of initial particle size and heating rate on gaseous products evolution of lignite pyrolysis at high temperature

Abstract

Pyrolysis is a key pathway for the clean and efficient utilization of lignite, which is important for achieving the dual carbon goals. However, under the naturally screened particle size system, the influence patterns of initial particle size and heating rate on the distribution of gaseous products from coal pyrolysis remain unclear. Therefore, this study systematically investigated the Effect of initial particle size and heating rate on gaseous products evolution of lignite pyrolysis under the naturally screened particle size system by comprehensively utilizing thermogravimetric analysis (TGA) and pyrolysis experiment on multiple lignite samples. The results revealed that the gas products yield exhibited a nonlinear variation pattern of increase-decrease-fluctuation-recovery within the initial particle size range of 0–13 mm, which were attributed to liptinite content, heat-mass transfer lag, thermal fragmentation, and heat-mass transfer lag, respectively. Meanwhile, the gas products yield showed a gradual decrease trend within the heating rate range of 40 °C/min as the heating rate increased due to reaction kinetics limitations and incomplete secondary reactions, with heat transfer effects contributing relatively less. This research gives new insights into the efficient pyrolysis of lignite from the perspectives of initial particle size and heating rate, and facilitates the study of the evolution mechanism of gaseous products during high-temperature pyrolysis.